CN-121995409-A - Intelligent reflecting surface-based beam forming and sea surface arrival angle estimation system and method

CN121995409ACN 121995409 ACN121995409 ACN 121995409ACN-121995409-A

Abstract

The invention discloses a beamforming and sea surface arrival angle estimation system and method based on an intelligent reflecting surface, wherein the system comprises an active intelligent reflecting surface arranged on the sea surface, an airborne array antenna and an airborne base station, wherein the airborne array antenna is arranged on a flying platform and is used for receiving radio frequency signals from a sea surface signal source and sending the radio frequency signals to the airborne base station, the airborne base station performs down-conversion processing on the radio frequency signals to separate analog baseband signals and performs dynamic beamforming processing based on the analog baseband signals, in the dynamic beamforming processing, digital baseband signals are firstly generated through sampling, phase shift matrixes and gain matrixes of the active intelligent reflecting surface are obtained in the duration of direction finding based on azimuth resolving and geometric analysis and AIRS beamforming, the rest digital baseband signals are used for dynamic beamforming of the active intelligent reflecting surface, and azimuth information of the sea surface signal source under the view angle of the airborne base station is obtained based on power statistics so as to realize DOA estimation.

Inventors

GONG YANYUN
WEN QINGLONG
WANG LING
SUN YANDONG
Gou Yuewen
TAO MINGLIANG
GUO ZIXUN

Assignees

西北工业大学

Dates

Publication Date: 20260508
Application Date: 20260119

Claims (10)

1. The system for estimating the angle of arrival and the wave beam forming based on the intelligent reflecting surface is characterized by comprising an active intelligent reflecting surface arranged on the sea surface, an airborne array antenna and an airborne base station, wherein the airborne array antenna and the airborne base station are arranged on a flying platform, and the system comprises the following components: The airborne array antenna is used for receiving radio frequency signals from a sea surface signal source and transmitting the radio frequency signals to the airborne base station; The method comprises the steps that an airborne base station performs down-conversion processing on radio frequency signals to separate analog baseband signals, and performs dynamic beam forming processing on the basis of the analog baseband signals, in the dynamic beam forming processing, digital baseband signals are generated through sampling, the digital baseband signals are subjected to direction finding duration time internal part based on azimuth resolving, geometric analysis and AIRS beam forming to obtain a phase shift matrix and a gain matrix of an active intelligent reflecting surface for dynamic beam forming of the active intelligent reflecting surface, and the rest digital baseband signals are subjected to power statistics to obtain azimuth information of sea surface signal sources under an airborne base station view angle to realize DOA estimation.
2. The intelligent reflection-surface-based beamforming and sea-surface angle-of-arrival estimation system of claim 1, wherein the on-board base station comprises a down-conversion processing board, a dynamic beamforming processing board, an air communication radio frequency link board, and a Beidou positioning module, wherein: the down-conversion processing board comprises a low-noise amplifier, a plurality of analog filters and an analog down-converter which are sequentially connected, the dynamic beam forming processing board comprises an AD sampling module, a channel correction module and an arbitration module which are sequentially connected, one path of output of the blanking module is sequentially connected with a signal azimuth resolving module, a geometric analysis module and an AIRS beam forming module, the other path of output is sequentially connected with a power statistics module and a coordinate system conversion module, and the Beidou positioning module is connected with the geometric analysis module and the coordinate system conversion module.
3. The intelligent reflection surface-based beam forming and sea surface arrival angle estimating system according to claim 1, wherein the radio frequency signals captured by the airborne array antenna reach the down-conversion processing board and are sent to the low noise amplifier to amplify the signal amplitude, the amplified signals are sent to the plurality of analog filters to carry out band-pass filtering to obtain analog intermediate frequency signals, the analog intermediate frequency signals are sent to the analog down-converter to carry out frequency mixing processing on the local oscillation signals and the analog intermediate frequency signals and filter the local oscillation signals to separate high-frequency carrier waves from analog baseband signals.
4. The intelligent reflection-surface-based beamforming and sea surface arrival angle estimation system according to claim 1, wherein the down-conversion processing board performs a total of P processes on radio frequency signals received by the airborne array antenna at each time t, and the analog baseband signals obtained after the processes are transmitted to the dynamic beamforming processing board: The AD sampling module performs total P times of sampling on the analog baseband signals in each time t, the analog baseband signals are processed by the down-conversion processing board to obtain digital intermediate frequency signals, the digital intermediate frequency signals obtained by each time of sampling are subjected to signal correction by the channel correction module to obtain digital baseband signals measured for the P time at the airborne end of the time t, then the current digital baseband signals are judged to flow to the signal azimuth resolving module or flow to the power counting module by the arbitration module, when P is an odd number, the digital baseband signals are judged to be conveyed to the signal azimuth resolving module by the arbitration module, and otherwise, the digital baseband signals are conveyed to the power counting module.
5. The intelligent reflection-surface-based beam forming and sea surface arrival angle estimation system according to claim 1, wherein when the decision is made as to a flow direction signal azimuth resolving module, the digital baseband signal is sent to the azimuth resolving module to perform arrival angle DOA estimation on the digital baseband signal at time t=0 based on a MUSIC algorithm, so as to obtain azimuth angle information under an on-board end view angle; the geometrical analysis module analyzes and calculates the real-time longitude and latitude coordinates of an active intelligent reflecting surface received by an AIRS communication radio frequency link plate in an airborne base station and the real-time longitude and latitude coordinates of a flying platform measured by a Beidou positioning module in the airborne base station to obtain the azimuth information of a sea surface signal source and the azimuth information of the flying platform under the AIRS visual angle, the two azimuth information are transmitted to an AIRS beam forming module, the AIRS beam forming module calculates a phase shift matrix and a gain matrix of the AIRS according to the two azimuth information, and the two matrices are returned to the active intelligent reflecting surface on the sea surface through the AIRS communication radio frequency link plate to realize dynamic beam forming on the active intelligent reflecting surface; And when the P-th measurement is completed, the power statistics module draws a success rate curve of the digital baseband signals corresponding to each azimuth, carries out peak searching processing, outputs azimuth information of the sea surface signal source corresponding to the peak under the visual angle of the active intelligent reflecting surface to the coordinate conversion module, and the coordinate conversion module outputs the received real azimuth information as azimuth information of the sea surface signal source under the visual angle of the airborne base station, so that an accurate DOA estimation result can be obtained.
6. The intelligent reflection-surface-based beam forming and sea surface arrival angle estimation system according to claim 1, wherein the active intelligent reflection surface comprises a main control board, a reflection unit driving board, an air communication radio frequency link board, a Beidou positioning module and a uniform area array reflection array; The AIRS communication radio frequency link board is used for receiving a phase shift matrix and a gain matrix sent by an onboard base station, the main control board sequentially changes the phase shift and the reflection gain of each reflection unit in the uniform area array reflection array through the reflection unit driving board according to the phase shift matrix and the gain matrix, so that dynamic beam forming is performed, and the Beidou positioning module is used for providing longitude and latitude coordinate information for the main control board.
7. The method for estimating the sea surface arrival angle and beam forming based on the intelligent reflecting surface is characterized by comprising the following steps of: the sea surface signal source radiates radio frequency signals to the surrounding through the omnidirectional antenna, the radio frequency signals reach the airborne array antenna after passing through the direct channel, and the airborne array antenna sends the received radio frequency signals to the down-conversion processing board for extracting analog baseband signals; The airborne base station performs dynamic beam forming processing on the basis of analog baseband signals, namely digital baseband signals are generated through sampling, the digital baseband signals are formed in the direction-finding duration time based on azimuth calculation and geometric analysis and AIRS beam forming, a phase shift matrix and a gain matrix of an active intelligent reflecting surface are obtained and used for dynamic beam forming of the active intelligent reflecting surface, and the rest digital baseband signals obtain azimuth information of sea surface signal sources based on power statistics.
8. The intelligent reflector-based beamforming and sea surface angle of arrival estimation method according to claim 7, wherein the processing procedure of the air beamforming module comprises: the AIRS beam forming module constructs a far field function of an AIRS reflected signal in the p-th measurement according to the received azimuth information Far field function with target And establishes an optimization problem: wherein exp is a natural exponential function, j is an imaginary unit; The phase shift introduced in the p-th measured digital baseband signal for the M-th row and N-th column of the reflection units of the uniform area array is realized, and the uniform area array of the active intelligent reflection surface shares M rows and N columns of reflection units, wherein d y and d x are the longitudinal center distance and the transverse center distance of each reflection unit; Constructing an AIRS local coordinate system by taking the normal vector of the uniform area array reflection array as the X axis, The local incidence azimuth angle and the incidence pitch angle are the local coordinate system; The emergent azimuth angle and the emergent pitch angle are; The phase shift introduced in the digital baseband signal measured for the p-th time for the reflection unit of the uniform area array reflection array; is azimuth and phase shift parameter; the target far field function is constructed as follows: Construction optimization problem: Wherein the method comprises the steps of For maximum signal gain of the active intelligent reflective surface air, 、 Representing the phase shift matrix and the gain matrix, respectively.
9. The intelligent reflection-surface-based beamforming and sea-surface arrival angle estimation method according to claim 7, wherein solving the optimization problem by genetic algorithm comprises: first build a size of Is a subject of (1): wherein the gene range is , 、 Gain coefficients and phase shift coefficients for the m-th row and n-th column of the AIRS; to minimize optimization problems, fitness functions are designed The following are provided: Selecting individuals in a tournament mode, continuously and randomly extracting the individuals from the population, calculating fitness, keeping two individuals with highest fitness as parents, performing simulated binary crossover to obtain offspring genes until the population quantity is recovered, and then respectively overlapping Gaussian disturbance in the genes of the offspring individuals as variation and performing constraint processing to complete one round of iteration; And after the preset rounds or the fitness function value is converged to a preset threshold value, an optimal solution can be obtained, so that a phase shift matrix and a gain matrix meeting constraint conditions are obtained.
10. The intelligent reflector-based beam forming and sea surface arrival angle estimation method according to claim 7, wherein when the receiver counter of the power statistics module reaches T, the power statistics module performs superposition analysis according to the following formula: Wherein the method comprises the steps of For the target power to be a target power, For the incident azimuth angle of AIRS local coordinate system in the p-th measurement process in time t The corresponding power statistics module receives the power of the digital baseband signal, wherein, , P is the total measurement times of the airborne base station to the radio frequency signals in the time t; the power statistics module calculates the azimuth angle scanning parameters Corresponding to The real azimuth information of the sea surface signal source can be obtained, and the real azimuth information is output to the coordinate system conversion module.

Description

Intelligent reflecting surface-based beam forming and sea surface arrival angle estimation system and method Technical Field The invention belongs to the technical field of radar detection, and particularly relates to a system and a method for beam forming and sea surface arrival angle estimation based on an intelligent reflecting surface, which are used for accurately estimating an arrival angle of a remote sea surface signal source under the condition that sea surface multipath effect exists remarkably. Background The continuous rapid development of marine economies places higher demands on the performance of marine communication technologies. Similar to terrestrial communication systems, various legacy and innovative applications in marine communication systems require high quality communication connections and strong perceptibility, while angle of arrival (DOA) estimation plays an important role in wireless communication systems and source location. The sea surface environment is often influenced by wind waves, fish activities, tides and other factors to form rough sea surfaces (sea waves) with different degrees, and the complicated multipath effect introduced by the rough sea surface environment can obviously influence the estimation accuracy of a sea surface DOA system. Meanwhile, the real-time and accuracy requirements on sea surface DOA estimation are gradually increased, and great challenges are brought to the estimation performance of a sea surface DOA system. Current sea surface DOA estimation techniques are typically implemented based on array antennas, with the general algorithms generally being as follows: MUSIC (Multiple Signal Classification) the technology that the MUSIC core is to construct a spatial spectrum function by utilizing the orthogonality principle of noise subspace and signal direction vector, and then determine the arrival Direction (DOA) of a signal source by searching the spectrum peak position on the spatial spectrum. The algorithm firstly collects array receiving data through an array antenna, calculates a sample covariance matrix according to the array receiving data, and then carries out characteristic decomposition on the sample covariance matrix to divide the sample covariance matrix into a signal subspace and a noise subspace. Based on the constructed signal subspace and the noise subspace, constructing a corresponding noise space spectrum function, and finally obtaining a corresponding DOA estimated value through spectrum peak search. However, in an environment where multipath propagation exists in rough sea or the like, the direct wave is highly coherent with the rough sea reflected wave. This strong coherence results in a signal covariance matrix with a different rank number than the incoherent signal sources, resulting in signal subspace spreading. Because the MUSIC algorithm requires that the signal sources are not coherent with each other, the diffusion of the signal subspace can cause the phenomenon that the estimated spatial spectrum thereof has spectrum peak splitting, shifting or completely vanishing, and finally serious deviation occurs to the DOA estimation result. In addition, dynamically changing ocean waves further exacerbate the degree of coherence of the signal. Thus, the conventional MUSIC algorithm is significantly degraded when faced with rough sea environments. Spatial smoothing (Spatial Smoothing) technology the core principle of the spatial smoothing technology is to divide a uniform linear array containing N array elements into K continuous subarrays with overlapping. And then, respectively calculating sample covariance matrixes of the receiving signals of all the subarrays, and averaging covariance matrixes of all the K subarrays to obtain a total covariance matrix with a full rank or an approximate full rank. The DOA estimation result is obtained by taking the reconstruction matrix as an input to access the algorithm based on subspace decomposition, such as MUSIC or Capon, and the like, instead of the original covariance matrix. The technology effectively breaks the correlation between the multipath signals with high coherence through the subarray averaging operation, so that the resolvable property of the covariance matrix is recovered, and the DOA estimation precision in the high coherence multipath environment is improved. However, when dealing with complex multipath effects caused by rough sea surfaces, the space smoothing technology still faces significant limitations, namely, firstly, the decoherence capacity of the technology mainly depends on the number K of subarrays, the increase of K can improve the decoherence effect, but the increase of K can also lead to the reduction of effective physical aperture of subarrays, so that DOA resolution is reduced, secondly, dynamically changing sea wave motion causes multipath signals to present non-ideal partial coherence characteristics, the processing effect of space smoothing is obviously weak